Method of inducing anaesthesia

ABSTRACT

AS AN ANAESTHETIC COMPOSITION FOR PARENTERAL ADMINISTRATION, AN AQUEOUS SOLUTION CONTAINING AT LEAST 1 MG./ML. OF 3A-HYDROXY-5A-PREGNANE-11,20-DIONE AND AT LEAST 1% BY WEIGHT OF A PARENTERALLY ACCEPTABLE NON-IONIC SURFACE ACTIVE AGENT HAVING AN HLB VALUE OF FROM 9-18. THE SOLUTION ALSO PREFERABLY CONTAINS TO INCREASE THE SOLUBILITY OF THE 3A-HYDROXY-5A-PREGNANE-11,20-DIONE, AT LEAST ONE STEROID OF THE FORMULA   3-(HO-),17-(R-O-CH2-CO-)-ANDROSTAN-11-ONE   WHEREIN R IS SELECTED FROM THE GROUP CONSISTING OF A LOWER ALKANOYL GROUP, A HEMISUCCINOYL GROUP AND A BENZOYL GROUP.

United States Patent 3,714,352 METHOD OF INDUCING ANAESTHESIA BenjaminDavis, Chalfont St. Peter, and Gordon Hanley Phillipps, Wembley,England, assignors to Glaxo Laboratories Limited, Greenford, Middlesex,England No Drawing. Filed June 17, 1970, Ser. No. 47,163 Claimspriority, application Great Britain, June 20, 1969, 31,371/69 Int. Cl.A61k 27/00 U.S. Cl. 424-243 Claims ABSTRACT OF THE DISCLOSURE As ananaesthetic composition for parenteral administration, an aqueoussolution containing at least 1 nag/ml. of3a-hydroxy-5a-pregnane-11,20-dione and at least 1% by weight of aparenterally acceptable non-ionic surface active agent having an HLBvalue of from 9-18. The solution also preferably contains to increasethe solubility of the 3a-hydroxy-5wpregnane-11,20 dione, at least onesteroid of the formula CHzOR wherein R is selected from the groupconsisting of a lower alkanoyl group, a hemisuccinoyl group and abenzoyl group.

This invention is concerned with improvements in or relating topharmaceutical preparations having anaesthetic activity, and moreparticularly aqueous preparations suitable for intravenous injection.

It has long been known that a number of steroids give rise to profounddepression of the central nervous system and act pharmacodynamically asanaesthetics or hypnotics. Such compounds have been the subject ofconsiderable study in an attempt to find anaesthetics to replace suchsubstances as thiopental sodium normally used but well known to beaccompanied by some degree of hazard or disadvantage. The literatureshows that very many steroid compounds have been studied in this regard.Reviews and discussions of some of the work carried out are to be found,for example, in Methods in Hormone Research (edited by Ralph I. Dorfman,vol. III, Part A, Academic Press, London and New York 1964, pp.415-475); H. Witzel, Z Vitamin, Hormon-Fermentforsch 1959, 10, 46- 74;H. Selye, Endocrinology, 1942, 30, 437-453; S. K. Figdor et al., J.Pharmacol. Exptl. Therap., 1957, 119, 299-309 and Atkinson et al., J.Med. Chem. 1965, 8, 426- 432.

It is stated in the Atkinson et al. paper that 3a-hydroxy-Sa-pregnane-ILZO-diOne and its succinate have approximately the samehypnotic activity as each other and their 55-epimers. The SB-epimer,named Predione, is described in French Pat. No. 6,555M, dated Dec. 23,1968, as an anaesthetic for intravenous injection in the form of anaqueous solution wherein it is solubilized by agents including Tween andEmulphor. This SB-epimer is reported by Kappas et al., AMA. Arch.Intern. Med., 105, pp. 701- 708 (1960) as causing pyrexia in man by boththe intramuscular and intravenous routes.

A thorough review of the literature indicates that anaesthetic steroidsgenerally possess poor activity and/or long induction periods. With suchcompounds a variety of undesired side effects such as paraesthesia andthrombophlebitis and vein damage have been noted. Many steroid compoundshaving anaesthetic action are also of poor solubility and thus muchresearch has hitherto been directed to the introduction of solubilisinggroups into such steroids, e.g. by the formation of partial esters withdior polybasic acids; such work has hitherto not resulted in thediscovery of a satisfactory anaesthetic steroid compound. Anaestheticsteroids are generally relatively simple pregnane derivatives, oftenhydroxylated in the 3-position, the general trend having been in thelatter case to study 3p-hydroxy compounds in preference to 3a-hydroxycompounds.

As a result of prolonged study of numerous steroids exhibitinganaesthetic activity we have found that 31:- hydroxy 5a pregnane11,20-dione (hereinafter called steroid I) has quite remarkableproperties as an anaesthetic. This substance has but poor solubility inwater and although referred to in the above cited literature as havinganaesthetic properties, has apparently been rejected by reason of itspoor solubility and the difiiculty to be anticipated in its use byintravenous administration arising therefrom.

We have found however that steroid I' can be brought into aqueoussolution with the aid of certain non-ionic surface active agents toyield solutions of a sufficient concentration for injection, theresulting solutions when injected showing excellent anaestheticproperties.

Thus the aqueous solutions of steroid I according to the inventioninduce anaesthesia and possess short induction periods, the anaestheticaction at suitable doses being indeed instantaneous; the solutions arethus excellent anaesthetics for inducing anaesthesia which is to bemaintained e.g. by an inhalation anaesthetic such as ether, halothane,nitrous oxide, trichloroethylene etc. The solutions are however capableof maintaining anaesthesia and analgesia to a suflicient degree toenable various surgical operations to be conducted without the aid of aninhalation anaesthetic, the required degree of anaesthesia beingmaintained if necessary by repeated administration (or even continuousadministration). Recovery from anaesthesia (where this is induced onlyby the solutions of this invention) is excellent, the patient exhibitinga feeling of wellbeing in distinction to the unpleasant after effectsgenerally associated with conventional anaesthetics. Moreover,anaesthetic solutions in accordance with the invention in general giverise to none of the undesired sideelfects hitherto associated withsteroidal anaesthetics.

According to the invention therefore we provide pharmaceuticalcompositions suitable for use by parenteral administration, comprisingan aqueous solution of at least 1 mg./ml. of3a-hydroxy-5a-pregnane-11,20-dione and at least 1% by weight of aparenterally acceptable nonionic surface active agent having an HLBvalue of from 9-18.

The non-ionic surface active agents used for the pur-- pose of thisinvention are generally those of the water soluble type, preferablyhaving an I-I-LB value of at least about 12, advantageously at leastabout 13. Preferably the HLB value of the surface active agent is notgreater than about 15. The surface active agent must naturally be onewhich is physiologically compatible, i.e. of itself give rise to nophysiologically unacceptable side effects in the dosages employed in theintended species to be treated (man or animal). Surface active agentsfor use in accordance with the invention are for example to be foundamong the following non-ionic surfactants and classes of surfactants:Polyoxyethylated derivatives of fatty (0 0 glyceride oils, e.g. castoroil, containing from 35 to 45 oxyethylene groups, per mole of fatty oil.Polyoxyethylene ethers (containing from to 30 polyoxyethylene groups) oflong chain alcohols (containing for example from 12-18 carbon atoms).

Polyoxyethylene polyoxypropylene ethers containing from to 35 and from15 to 30 oxyethylene and oxypropylene groups respectively.Polyoxyethylene ethers (containing from 6 to 12 oxyethylene groups) ofalkyl phenols the alkyl groups of which preferably contain 6-10 carbonatoms.

Polyoxyethylated (containing from 15 to 30 oxyethylene groups) fattyacid (e.g. C esters of sugar alcohol anhydrides e.g. sorbitan ormannitan. Long-chain (e.g. C alkanoyl monoand di-alkanolamides (thealkanol portions of which for example contain 1-5 C atoms) for example lauroyl monoand di-ethanolamides. Polyethylene glycol esters (containingfrom 6 to 40 ethylene oxide units) of long chain fatty acids (containingfor example 12-18 'C atoms) e.g. polyethyleneglycol monooleate(containing for example 8 ethylene oxide units).

Examples of non-ionic surface active agents, of the foregoing types,useful in accordance with the invention include:

Cremophor EL, a polyoxyethyl ated castor oil containing about 40ethyleneoxide units per triglyceride unit;

Tween 80, polyoxyethylene sorbitan monooleate containing about ethyleneoxide units;

Tween 60, polyoxyethylene sorbitan monostearate containing about 20ethylene oxide units; and

Tween 40, polyoxyethylene sorbitan monopalrnitate containing about 20ethyleneoxide units.

The expression solutions is used herein to denote liquids which have theappearance of true solutions and are thus optically clear and capable ofpassage, for example, through a micro-porous filter, irrespective ofwhether such solutions are true solutions in the classical chemicalsense and irrespective of whether they are stable or metastable. Thus itmay be that the steroid is associated with micelles. The solutions ofthis invention, irrespective of their precise physical nature, behave astrue solutions for the practical purpose of intravenous injection.

We have further found that the total amount of anaesthetic steroid whichmay be dissolved in accordance with the invention may be substantiallyincreased by the presence of a steroid of general formula [wherein R isan alkanoyl group having a straight or branched chain (containing forexample 2-4 carbon atoms which may, if desired be substituted, forexample by a carboxyl group) or an unsubstituted or substituted aroyl oraralkanoyl group]. Such steroids of Formula II thus act as solubilitypromoters for the steroid I and are capable of substantially increasingthe amount of the latter which may be dissolved in the compositions ofthis invention. Moreover steroids of Formula II, preferred members ofwhich are those in which R is an acetyl, propionyl, isobutyryl,hemisuccinoyl or benzoyl group, themselves possess anaesthetic activityalthough of a generally lower order than steroid 1. Solutions containingsteroid I together with a steroid of Formula II may thus be preparedhaving a substantially greater anaesthetic potency than a solution ofsteroid I alone, due to the increased amount of steroid I which can bedissolved and the anaesthetic action of the steroid of Formula II perse.

Compounds of Formula II above are new compounds, and constitute afurther feature of the invention.

The proportion of surface active agent to be used in the compositions ofthis invention depends upon its nature and upon the concentration ofsteroid desired in the final composition.

In preferred compositions according to the invention the proportion ofsurfactant is preferably at least 5% by Weight and advantageously above10% by weight. A very convenient proportion of surfactant has been foundto be 20% by weight but 30% and up to 50% may be used. The proportionsof surfactant are expressed by weight in relation to the total volume ofthe composition in metric units.

The compositions according to this invention may contain up to 40 oreven 50% by weight of the total steroid of a compound of Formula H; aslittle as 5% of the total steroid present of a compound of Formula IIprovides useful solubility promotion. For practical purposes it ispreferred that of the total steroid at least 10% by weight, andpreferably not more than 30% by weight of the total steroid consists ofa compound of Formula II. Very satis factory results have been achievedwith a mixture of steroid I with a steroid of Formula II in which theproportion of the steroid of Formula II is about 25%.

As will be clear, the proportion of steroid I in the aqueous solutionaccording to the invention depends upon the nature and amount of surfaceactive agent used and also upon the amount of steroid of Formula IIpresent (if used). The composition will contain at least 1 mg./ml. ofsteroid I and solutions can be made containing for example 2 and 4mg./ml.; using a steroid of Formula II as solubiliser the amounts oftotal steroid can be increased up to 50 mg./-ml. although less than 30mg./ml. total steroid and generally less than 20 rug/ml. will usually besatisfactory. A composition comprising 9 mg./ml. of steroid I to 3mg./ml. of a compound of Formula II in which R is acetyl has been foundto be very satisfactory.

In all cases, as stated above the relative proportion of the variouscomponents are adiusted to give a clear solution.

In a preferred method of preparing the solutions according to theinvention the steroid is first dissolved in the selected surfactant forexample, with heating and the resulting solution dissolved in water.Alternatively the steroid may be dissolved in a volatile organic solventadvantageously having a boiling point of less than about C. which ismiscible with the surface active agent such as a volatile loweraliphatic ketone e.g. acetone or methyl ethyl ketone or a volatilehalogenated hydrocarbon e.g. chloroform or methylene chloride. Acetoneis particularly preferred for this purpose. The surface active agent isthen added to this solution, the organic solvent removed by evaporation,for example by passing a stream of an inert gas through the solutione.g. nitrogen and the resulting solution of steroid in surfactant ismixed with Water. By these procedures in general it is possible todissolve increased amounts of steroid I as compared with other methods.

The solutions may also be prepared by shaking the steroid with anaqueous solution of the surface active agent.

In all cases simple tests enable one to determine the relativeproportions of surface active agent required.

The anaesthetic solutions according to the invention are generallyadministered by intravenous injection although as is known in theanaesthetic art in certain cases, e.g. with young children intramuscularinjection might be preferred.

As is usual in the case of anaesthetics, the quantity of steroid I usedto induce anaesthesia depends upon the weight of the individual to beanaesthetised. For intravenous administration in the average man a doseof from 0.45 to 3.5 mg./kg. will in general be found to be satisfactoryto induce anaesthesia, the preferred dose being within the range of from0.7 to 2.5 mg./kg. Generally a dose of about 1.35 mg./kg. is verysatisfactory. The dose will naturally vary to some extent dependent uponthe physical condition of the patient, and the degree and period ofanaesthesia required, all as is well known in the art. It is thuspossible by adjustment of the dose to achieve durations of anaesthesiavarying from about minutes to up to an hour or more. If it is desired tomaintain prolonged anaesthesia, repeated doses of the solutions of thisinvention may be used, such repeated doses being generally either ofthesame order or lower than the original dose. Alternatively continuousadministration may be undertaken at for example a rate of 0.09-l.8mg./kg./min.

Where the anaesthetic solutions are administered intramuscularly,naturally higher doses are generally necessary.

3a-hydroxy-5u-pregnane-l1,20-dione (steroid I) can be prepared in anyconvenient manner for example as described by Camerino et al., Helv.Chim. Acta., 1953, 36, 1945 or by Nagata et al., Helv. Chim. Acta.,1959, 42, 1399. In applying the last-mentioned process we haveencountered various difliculties at several stages due to sidereactions, which we have found to be due to epimerisation at position17. As a result of further work we have developed a new synthesis ofsteroid I based essentially upon the synthesis of Nagata et al. butworking essentially with intermediates having A -unsaturation. Our newsynthesis provides generally better yields and affords greater ease ofworking and purity of product, due essentially to the impossibility ofepimerisation at position 17 in compounds of the A series.

Thus in accordance with our new synthesis Bot-hydroxy-5a-pregnane-ll,20-dione is prepared by hydrogenation of 3 a-hYClIOXY-Sa-pregn-l 6-ene-l 1,20-dione.

The hydrogenation may be conveniently effected in an organic solvent,for example an alkanol or an ether e.g. methanol, ethanol, propanol,diethyl ether or tetrahydrofuran. A catalyst is preferably used toeffect the hydrogenation for example palladised charcoal, Raney nickel,platinum catalysts and the like.

3u-hydroxy-5a-pregn-16-ene-l1,20-dione may, for example, be prepared bysolvolysis of the 3a-acyloxy group of a3a-acyloxy-5a-pregn-16-ene-l1,20-dione. The acyloxy group at the3ot-position may, for example, be a formyloxy, acetoxy, propionyloxy,butyryloxy or benzoyloxy group.

Advantageously, the solvolysis may be effected by bydrolysis, preferablyunder alkaline conditions although both acidic and alkaline hydrolysesmay be used. The hydrolysis may, for example, be effected in thepresence of a solvent such as an alkanol or an ether, e.g. methanol,ethanol, propanol, iso-propanol, butanol, t-butanol, diethylether,dioxan or tetrahydrofuran. The reaction may be effected at anyconvenient temperature, for example, at ambient temperature or anelevated temperature, advantageously at the boiling point of the solventused. Suitable alkalis for the hydrolysis include, for example, alkalimetal hydroxides e.g. sodium or potassium hydroxide.

The 3a-acyloxy-5a-pregn-16-ene-l1,20-diones which may be used for thepreparation of the corresponding 3ahydroxy compound may, for example, beprepared from a corresponding3fl-hydrocarbonsulphonyloxy-Su-pregnl6-ene-ll,2-0-dione e.g.3fl-tosyloXy-5a-pregn-l6-ene-l1, -dione and this reaction will be seento be an inversion reaction in which the configuration at position-3 ischanged from [3 to 0:.

According to this method, the 3fi-sulphonate may be reacted with theappropriate carboxylic acid in solution in a solvent medium to yield thedesired 3a-acyloxy compound. This reaction is preferably effected in thepresence of alkali metal ions it being convenient to use the carboxylicacid in the form of an alkali metal salt thereof e.g. the sodium orpotassium salt. Suitable solvents include for example dimethylsulphoxideand N-alkylamide solvents, e.g. dimethylformamide and dimethylacetamide.Preferably the solvent is water miscible and contains water (for exampleup to 20%) which generally serves to accelerate the reaction.Advantageously the carboxylic acid is an aliphatic carboxylic acid,lower alkanoic acids being preferred, for example, formic, acetic,propionic or butyric acids or an aromatic carboxylic acid e.g. benzoicacid. Preferred salts are the sodium and potassium salts. Generallyfavourable results are obtained by the use of potassium acetate. Thesolvent used may be the carboxylic acid itself or an anhydride thereof(provided that such acid or anhydride is liquid at the reactiontemperature) alkali metal ions being provided by an alkali metal salte.g. of the carboxylic acid. For example when using aqueous formic acid,alkali metal ions which may be present may, for example, be provided byan alkali metal formate or an alkali metal hydrogen carbonate e.g.potassium formate or potassium hydrogen carbonate. The inversion of theconfiguration of the substituent at the 3- position of the5ot-pregn-l6-ene-l1,20-dione may be effected at any convenienttemperature, advantageously at an elevated temperature, suitableconditions being found by preliminary experiment.

An alternative method of converting the above-mentioned 3,8-sulphonatesto the corresponding 3a-hydroxy compounds involves treatment of thesulphonates under alkaline conditions using for example an alkali metalhydroxide, e.g. NaOH, in a polar solvent e.g. ethanol, methanol, dioxanetc.

The inversion of the configuration of the substituent from the3fi-position to the Set-position may also be effected in the presence ofdimethylformamide, or dimethylacetamide preferably in the presence ofwater e.g. analogous to the method described by Chang and Blickenstaff(J. Amer. Chem. Soc., 1958, 80, 2906), and Bharucha et al. (Can. J.Chem. 1956, 34, 982). This method when applied, for example, to thetosylate of 3fl-hydroxy-5apregn-l6-ene-11,20-dione produced thecorresponding 30:- formate together with some of the corresponding freehydroxy compound. Dimethyl acetamide may also be used, preferably underaqueous conditions, to form the 3a-acetoxy compound by inversion.

3p hydrocarbon sulphonyloxydu-pregn-l6-ene-11,20- diones may, forexample, be prepared according to conventional methods. Thus the3,8-hydroxy compound may be reacted with a hydrocarbon sulphonyl halide,for example p-toluene sulphonyl chloride, preferably in the presence ofa tertiary base e.g. pyridine, collidine, N- methyl morpholine etc., thetertiary base, if desired, also acting as solvent. The sulphonylationreaction may, for example, be effected at a temperature of from 50 to 50C., preferably 0 to 25 C.

In carrying out the process according to the invention for thepreparation of 3a-hydroxy-5a-pregnane-l1,20- dione, good overall yieldsfrom 3fi-hydroxy-5a-pregn-16- ene-ILZO-dione may be obtained by theomission of purification of at least some of the intermediates. Thisprocess also has the advantage of comparative ease of purification of3a-hydrOXy-Su-pregnane-I1,20-dione from the corresponding S-desoxycompound formed as a byproduct in the process from the corresponding2,16-diene formed by elimination of the hydrocarbon sulphonyloxy groupin the inversion step. Good overall yields from 35-hydroxy-5u-pregnane-l1,20-di0ne of high purity, may be achieved usingpotassium acetate in aqueous dimethylformamide in the inversion step.Improved results may be obtained by partial purification of the reactantused in the hydrogenation step.

3u-hydroxy-5u-pregn-16-ene-l1,20-dione may also be prepared by hydrationof 5u-pregna-2,l6-diene-11,20 dione which may be formed by theelimination of the hydrocarbon sulphonyloxy group from the correspondingEBB-hydrocarbon sulphonyloxy compound. The hydration may, for example,be effected to the reaction with a mercury compound, preferably underacid conditions to form an oxymercurial intermediate which is thendecomposed by reduction. For example, the oxymercuration may be carriedout using mercuric acetate, mercuric sulphate or mercuric oxide in asolvent such as dioxan or tetrahydrofuran (preferably aqueous)advantageously in the presence of a strong acid e.g. perchloric acid,nitric acid, or sulphuric acid. Decomposition of the oxymercurialinter-mediate may for example be effected by reduction with an alkalimetal borohydride e.g. sodium or potassium borohydride, preferably inthe presence of aqueous alkali e.g. aqueous caustic soda.

3fl-hydroxy-5a-pregn-l6-ene-l1,20-dione may be prepared from35-acetoxy5a-pregn l6 ene-ll,20-dione (Chamberlin et al., J. Amer. Chem.Soc., 1951, 73, 2396). Hydrolysis of the 3B-acetoxy compound may beeffected by conventional methods, for example under alkaline conditions,e.g. in solution in acetone, an alkanol or ether such as methanol,ethanol, propanol, t-butanol, diethyl ether, dioxan or tetrahydrofuran.Suitable alkalis may, for example, be alkali metal hydroxides e.g.potassium hydroxide.

Steroids of general Formula II above are new compounds and constituteanother feature of the invention. The preferred compounds of Formula IIfor use as solubilising agents in pharmaceutical preparations are thosein which the 2l-acyloxy group is a 2l-acetoxy, 2lpropionyloxy,2l-isobutyryloxy or ZI-benzyloxy group.

2he ZI-acyloxy compounds of Formula II above may be prepared by anyconvenient method. We have found however that such compounds areadvantageously prepared by reaction of a compound of formula OOCH;

(rrr) H (in which R represents a hydroxy or protected hydroxy group e.g.a nitrate, trimethylsilyloxy or trichloroethoxy carbonyloxy group) witha lead tetraacylate preferably in the presence of a Lewis acid, and,Where R represents a protected hydroxy group, subsequent conversion ofsaid group to a hydroxy group. Protection of the 3a-hydroxy group of thecompound of Formula III however, is not essential before theacyloxylation reaction.

The lead tetra-acylate used may be for example lead tetraacetate. TheLewis acid may for example be boron trifluoride, conveniently used asits etherate. We have found, for example that the presence of borontrifluoride improves the rate of reaction and can enable lowertemperatures of reaction to be employed, thus, in many cases, thereaction proceeds satisfactorily at ambient temperature, i.e. in theabsence of applied heat.

The yield obtained by this process is frequently better than thatobtained at an elevated temperature in the absence of boron trifluorideand the fact that the reaction rate is faster and thus lowertemperatures can often be used means that this process possesseseconomic advantages on the large scale. The ability to operate at lowertemperatures also means that there may be less likelihood of undesiredside reactions taking place.

The acyloxylation of compounds of the Formula HI may be carried out in asolvent medium comprising a mixture of a hydrocarbon solvent and analcohol. Suitable hydrocarbon solvents are, for example, benzene ortoluene and the alcohol may, for example, be methanol. Advantageouslythe solvent comprises a mixture of benzene and methanol in the ratio of19: 1.

The acyloxylation is especially suitable for acetoxylation using leadtetraacetate but other lead acylates, e.g. lead tetrapropionate may, ofcourse, be used with the formation of the corresponding 21-propionyloxycompound.

The 3tz-trimethylsilyloxy compounds of Formula III (R representing atrimethylsilyloxy group) may, for example, be prepared by the reactionof the parent Bot-hydroxy compound of Formula III (R representing ahydroxy group) with a trimethylsilyl halide e.g. trimethylchlorosilaneor hexamethyl disilazane in the presence of a tertiary base e.g.pyridine and, if desired, in the pres ence of a solvent e.g. ahalogenated hydrocarbon such a methylene chloride or tetrahydrofuran.The reaction may conveniently be etfected at room temperature or ifdesired, at lower temperatures e.g. 0 C. The trimethylsilyloxyprotecting group is generally automatically removed during theacyloxylation.

The 3ot-trichloroethoxycarbonyloxy compound of Formula III may beprepared by reaction of the parent 3ahydroxy compound with analkylchloroformate, e.g. trichloroethyl chloroformate, preferably in thepresence of an acid binding agent e.g. a tertiary amine such aspyridine, conveniently in a solvent such as dioxan or tetrahydroturan.The trichloroethoxy carbonyl protective group may subsequently beremoved by reduction for example using a metal/ acid system such as zincand acetic acid.

The Fla-nitrate of Formula III may be prepared by reaction of the parent3a-hydroxy compound with fuming nitric acid and acetic anhydridepreferably in the presence of a solvent e.g. chloroform. The nitrateprotection group may subsequently be removed by reduction, for example,using a metal acid system such as zinc and acetic acid or catalytichydrogenation using for example, palladium on charcoal as catalyst.

Other methods for the preparation of the Zl-acyloxy compounds of Formula11 above may also be used. Thus a 2l-acyloxy-5a-pregnane-3J1,20-trionemay be reduced, for example, using an enzymatic method such as reductionwith brewers yeast (Saccharomyces cerevisiae). This method is convenientfor the preparation of Zl-alkanoyloxy compounds such as the 2l-acetoxycompound.

Compounds of Formula II may also be prepared via the corresponding2l-chloro, Zl-bromo or 21-iodo compounds. We prefer to proceed via the21-bromo intermediate which may be prepared from 5a-pregnan-3a-ol-1L20-dione. The bromination is effected for example using molecular bromine,in a solvent such as methanol or ethanol advantageously at a temperatureof from --1D to +30 C. The reaction is preferably conducted in thepresence of a catalyst such as acetyl chloride or hydrogen bromide inacetic acid. The 2l-halogeno compound may then be converted into thedesired 2l-acyloxy compound by reaction with the salt of correspondingcarboxylic acid, such as an alkali metal salt e.g. the potassium salt ora tertiary amine salt conveniently N-methylmorpholine orN-ethylpiperadine or a trialkylammonium salt e.g. the triethylammoniumsalt. The reaction is preferably carried out in a solvent for exampleacetone or methanol, advantageous- 1y under anhydrous conditions.

An alternative method, particularly convenient for the preparation ofcompounds of the Formula II in which R is other than an acetyl group,comprises acylating a compound of formula COCHzOH (wherein R representsa protected hydroxy group) and deprotecting the 3e-hydroxy group of the21-acyloxy derivative of the compound of Formula IV produced. Thecompound of Formula IV is conveniently prepared by the deacylation of a21-acyloxy derivative of a compound of Formula IV, for example a21-acetoxy derivative thereof, and provides a method for converting onecompound of Formula II for example in which R is acetyl to anothercompound of Formula II in which R is a different acyl group. The21-acetyl compound of Formula II may thus, for example, be coverted intoanother 21-acyl com pound of Formula II by firstly protecting the3ot-hydroxy group with a protecting substituent which may be removedunder acidic, reductive or other conditions but is stable under alkalineconditions, such as a 3a-ether substituent e.g. a tetrahydropyranyl ortriphenylmethyl substituent or preferably a 3a-nitrate ester,hydrolysing the 3u-protected compound to yield the corresponding21-hydroxy compound, under basic conditions, preferably in the presenceof potassium or sodium hydrogen carbonate, conveniently in the presenceof a solvent e.g. methanol, ethanol or tetrahydrofuran, reesterifyingthe resultant product and removing the 3a-protecting substituent.

The reesterification is preferably effected using the anhydride orchloride of the desired acid preferably in the presence of a tertiaryamine (e.g. pyridine, collidine, or dimethylaniline) which may alsoserve as solvent for the reaction.

The protecting group at position 3 may be removed in conventionalmanner, conditions may be chosen which will not eflect the rest of themolecule. Thus for example when the 3a-hydroxy group of the compound ofFormula II is protected by the formation of a nitrate ester, the nitrategroup may be removed by acid hydrolysis of the compound for exampleusing aqueous mineral acid, or by reduction using, for example zinc andacetic acid or by catalytic hydrogenation using, for example, palladiumon charcoal as catalyst.

The following examples are given by way of illustration only, alltemperatures being in degrees centigrade.

EXAMPLE 1 3 fi-hydroxy-S a-pregn-16-ene-1 1,20-dione A solution of3,13-acetoxy 5a pregn 16 ene-11,20- dione (Chamberlin et al., J. Amer.Chem. Soc], 1951, 73, 2396) (25.7 g.) in dioxan (Analar, 500 ml.) wastreated with potassium hydroxide g.) and Water 250 ml. and the mixtureallowed to stand at room temperature for 1 hour. After a further 1 hourat 40 the mixture was diluted with water and the product filtered off.The crude material was dissolved in chloroform and filtered through acolumn of grade III neutral alumina (ca. 100 g.). The material obtainedwas crystallised from acetonepetroleum to give pure 3 8-hydroxy 5apregn-16-ene- 11,20-dione (17.65 g., 77.5%) as small plates, M.P. 217.5,[otJ +82.9 (C, CHCl 1.1), A 234 nm, (6 10,100). (Found: C, 75.9%; H,9.3%. C H O requires C, 76.3%; H, 9.2%.)

EXAMPLE 2 3,6-toluene-p-sulphony10xy-Sa-pregm16-ene-11,20-dione Asolution of 3fl-hydroxy 50c pregn-16 ene-11,20- dione (39.6 g.) in drypyridine (165 ml.) was treated with toluene-p-sulphonyl chloride (43.9g.) to give the toluene sulphonate (56.7 g.), M.P. 147-151. A portion(10.7 g.) of this material was crystallised from ethyl acetate-petroleumto give the pure toluenesulphonate (9.2 g.) as plates, M.P. 154-155",[a] +42.8 (C., CHCl 1.2), k 226 nm. (6 20,780). (Found: C, 69.6%; H,7.4%; S, 6.5%. C H O S requires C, 69.45%; H, 7.5%; S, 6.6%.)

EXAMPLE 3 3a-hydroxy-5a-pregn-16-ene-1 1,20-dione A solution of3B-toluene-p-sulphonyloxy-Sa-pregn-16- ene-11,20-dione (19.1 g.) inN,N-dimethylformamide (160 ml.) and water (16.0 ml.) was treated withpotassium acetate (29.2 g.) and the mixture heated at 115 (completesolution on heating) for 2 /2 hours. The solvents were removed in vacuoand the residue partitioned between chloroform and water. The chloroformextract was washed with water, dried and evaporated. The residue wastaken up in methanol (500 ml.) and the solution flushed with nitrogen.Potassium hydroxide (17 g.) in water ml.) was added and the solutionrefluxed for 1 hour. Glacial acetic acid was added to bring the pH toabout 6 and most of the methanol evaporated in vacuo. Dilution withwater gave a gummy precipitate which was extracted into chloroform togive the crude product. This material was extracted with ether and theresidue boiled with benzene. The insoluble material was crystallisedfrom chloroform-petroleum to give Ba-hydroxy 5a pregn-16-ene-11,20-dione (3.28 g.) as large prisms, M.P. 243- 244, [ab +86.5(C., OHCl 0.8), A 233 nm. (a 9,530). (Found: C, 76.6%; H, 9.2%. C H Orequires C, 76.3%; H, 9.15%.)

EXAMPLE 4 3 a-hydrOXy-Sa-pIegnane-I 1,20-dione From 3ot-hydroxy 5apregn-l6-ene-11,20-dione: A solution of 3a-hydroxy 5a pregn 16ene-11,20-dione (200 mg.) in freshly distilled tetrahydrofuran (8 ml.)with 5% palladium on carbon (100 mg.) was hydrogenated till hydrogenuptake ceased. The mixture was filtered through a pad of kieselguhr andthe tetrahydrofuran removed in vacuo to give3ot-hydroxy-5wpregnane-11,20-dione (196 mg), M.P. 171-172", [111 +112.5(C., CHCl 1.0).

EXAMPLE 5 3u-hydroxy-5a-pregnane-1 1,20-dione A solution of 38-acetoxy-5ot-pregn-16-ene-11,20-dione (50 g., 0.134 mole) in dioxan(1,050 ml.) was flushed with nitrogen and treated with potassiumhydroxide (20 g., 0.356 mole) then nitrogen flushed water (535 ml.). Thesolution was stored at 40 for 1 hours then at room temperature for 1hour. Glacial acetic acid was added (to pH ca. 7), the organic solventremoved in vacuo until crystallisation started and the resulting mixturediluted with water (ca. 1,500 ml.). The precipitated solid was filtered01f, washed with water (until washings were neutral) and dried overphosphorus pentoxide in vacuo. This gave the alcohol (39.9 g., theory)as an off-white crystalline solid, M.P. 216-218", [a1 +82.9 (C. 1.0,CHCl )t 234 nm. (5 9,210).

An ice-cold solution of toluene-p-sulphonyl chloride (96 g., 0.505 mole)in dry pyridine (180 ml.) was added to an ice-cold solution of the abovealcohol (86 g., 0.26 mole) in dry pyridine (180 ml.). The dark orangesolution was allowed to warm to room temperature and kept at thattemperature for 16 hours. The mixture was cooled to 0 and sufficientwater (ca. 20 ml.) added to dissolve the precipitated pyridinehydrochloride. The clear solution was kept at room temperature for 2hours then diluted with 2 N-hydrochloric acid (2.5 1.). The precipitatedcrystalline solid was filtered 01f, washed with 2 N-hydrochloric acid(500 ml.) then water (until washings were neutral) and dried in vacuoover phosphorus pentoxide to give the tosylate (120 g., M.P. 147150decomp., [11],; +386 (C. 1.0, CHCl A mixture of the tosylate (60 g.;0.124 mole) in N,N- dimethylformamide (350 ml.) and potassium acetate(92 g., 0.94 mole) in water (35 ml.) was stirred at 115 for 4 hours. Thebrown solution was cooled and most of the N,N-dimethylformamide removedby evaporation at 50 and 4 mm. to give a brown solid mass. Another runwith tosylate (58 g., 0.12 mole), potassium acetate (90 g., 0.91 mole),N,N-dimethylformamide (350 ml.) and water (35 ml.) was carried out asdescribed above. The combined residues were shaken with chloroform, thechloroform layer separated and washed with more water (ca. 200 ml.). Thecombined aqueous fractions were extracted with chloroform (3 X ml.) andthe combined chloroform extracts (including those above) were washedwith 1 1 water (3X 100 ml.) and dried over magnesium sulphate. Thechloroform was removed in vacuo and residual N,N- dimethylformamide wasevaporated at 50 and 4 mm. to give the crude Swacetate (92 g.) as abrown solid.

A solution of the crude acetate (92 g.) in dioxan (1,000 ml.) was mixedwith a solution of potassium hydroxide (45 g., 0.8 mole) in water (500ml.) to give a two-phase system. A homogeneous solution was obtained bythe addition of dioxan (440 ml.) and water (625 ml.). Nitrogen wasbubbled through the solution which was heated at 50 for 2 hours. Theport coloured solution was treated with glacial acetic acid (ca. 40 ml.)to bring the pH to about 7 and two thirds of the solvent was removed bydistillation in vacuo (water pump). Water (ca. 3 l.) was added to theresultant mixture (which had already begun to crystallise) and theprecipitated solid was filtered off, washed with water and dried overphosphorus pentoxide to give the crude 3a-alc'ohol (73.9 g.).

A solution of the above crude alcohol (73.8 g.) in tetrahydrofuran (1900ml., freshly distilled) with 5% palladised charcoal (25 g.) washydrogenated at atmospheric pressure and room temperature. After 1%hours hydrogen uptake (ca. 71) ceased. The catalyst was filtered off ona kieselguhr pad and the filtrate was concentrated in vacuo to acrystalline mass (71.3 g.).

This material was dissolved in chloroform and filtered through a columnof grade III neutral alumina (150 g.) which was washed with chloroform(total ca. 400 ml.). The chloroform was removed in vacuo and the residuetaken up in acetone (200 ml.). Acetone (100 ml.) was boiled off and thesolution was diluted (with stirring) with petroleum (ca. 2 1.). Theprecipitated solid was collected by filtration, washed with petroleumand dried to give the crude alcohol (47.1 g.), M.P. 161-163".Retreatment with acetone-petroleum gave material (38.3 g.), M.P.165-168", and a second crop (3.0 g.), M.P. 167-l68, as fine needles. Afurther treatment of these combined crops afforded purer material (33.8g. plus a 5.3 g. second crop), M.P. 168-169 (97.2% pure on G.L.C., 45.5%yield based on 3,8-alcohol). A final treatment gave3u-hydroxy-5a-pregnane-11,20-dione (35.1 g, 40.8% yield based on3p-alcohol; 46.7% yield based on 3fl-acetate) as needles, M.P. l68170,{ab +lll.6 (C. 1.0, CHCI (Found: C, 76.15%; H, 9.6%. Calcd. for C l-1 C,75.9%; H, 9.7%.) Purity by G.L.C. analysis was 97.7%.

Chromatography of the combined residues on grade III neutral aluminagave a further amount (9.3 g.) of 3ahydroxy-a-pregnane-1 1,20-dione.

EXAMPLES 6-16 The table records gas-liquid chromatographic analysis ofmixtures of 3a-acetoxy (and/or formyloxy)-5a-pregnl6-ene-ll,20-dione,3a-hydroxy-5a-pregn-16-ene 11,20- dione and5a-pregn-2,l6-diene-l1,20-dione formed by solvolysis of3fi-tolnene-p-sulphonyloxy-Su-pregn-l6-ene- 1 1,20-dione.

1 2' EXAMPLE l7 3a-hydroxy-5a-pregn-16-ene-1 1 ,20-dione5a-pregna-2,16-diene-l1,20-dione (700 mg., 2.2 mmole) was dissolved intetrahydrofuran (10 1111.), and water (4 ml.) was added. Mercuricacetate (700 mg., 2.2 mmole) was added to the stirred solution to givean immediate yellow precipitate. The reaction mixture was stirred atroom temperature for 24 hours, and then 3 M sodium hydroxide solution (3ml.) and 0.5 M sodium borohydride in 3 M sodium hydroxide solution(about 3 ml.) were added until all the yellow complex had been reduced.The tetrahydrofuran layer was separated, washed with sodium chloridesolution, and then diluted with ether (100 ml.). The organic solutionwas washed well with Water, dried, and evaporated to give a white oilysolid, which was purified by preparative thin-layer chromatography andrecrystallisation from ethyl acetate/petroleum to give3a-hydroxy-5a-pregn-l6-ene-11,20-dione (160 mg., 22%) as colourlesscrystals, M.P. and mixed M.P. with an authentic sample, 234-237", [0:];+86.5 (C. 1.1, CHCI EXAMPLE 18 21-acetoxy-3a-hydroxy-5a-pregnane-11,20-dione Boron trifluoride etherate (37.9 ml.) was added to a stirredsolution of 3m-hydroxy-5a-pregnane-l1,20-di0ne (6.64 g., 20 mmole) andlead tetraacetate (10.1 g., 22 mmole) in dry benzene v (280 ml.) andmethanol (15.1 ml.) at room temperature. After 2 hours the mixture waspoured into water (2 l.) and extracted with ether (1 1.). The combinedether extracts were washed successively with sodium bicarbonate solutionand water, dried over magnesium sulphate, and concentrated in vacuo togive a white crystalline mass. Four recrystallisations from acetonepetroleum (B.P. 406 gave 2l-acetoxy-3ot-hydr0xy-5a-pregnane-11,20-dioneas fine needles (4.22 g., 54%), M.P. 172-173", [041 +104 (C. 1.0, CHCI(Found: C, 70.8%; H, 8.9%. C H O requires C, 70.8%;H, 8.8%.

EXAMPLE 19 2 l-acetoxy-3u-hydroXy-Saregnane-1 1,20-dione via atrimethylsilyl derivative Trimethylchlorosilane (0.33 ml., 1.5 equiv.)and pyridine (0.485 ml., 2 equiv.) were added to a solution of3ahydroxy-sm-pregnane-l1,20-dione (1.0 g.,) in methylene chloride (16.6ml.) at room temperature. After 16 hours at 0 more trimethylchlorosilane(0.33 ml., 1 equiv.) was added and after a further 1 /2 hours thesolvent was removed in vacuo. Ether was added to the residue and thewhite solid was filtered 011. The ether Was removed in vacuo and theresidue tritnrated with a little petroleum (B.P. 40-60) to give3a-trimethyl-siloxy-Sa-pregnane- 11,20-dione (0.2 g.), M.P. -96. Thiscompound was also prepared by the use of hexamethyldisilazane andtrimethylchlorosilane in tetrahydrofuran.

DISPLACEMENT REACTIONS ON 3B-TOLUENE-p-SULPHONYLOXY- 5a-PREGN-16-ENE-11,20-DIONE Weight Percent 30:-

o! CHgCO Ex. tosylate, Other Temp., plus 3a- Percent Total percentPercent No. g. Solvent volume (1111.) reactants (g.) Time, hrs. 0. HO OzSui-OH 011 0 01-- A 6 0. 66 D.M.F. (10) 1.11003 (0.64) 3 3 1 1 5 7 43. 712. 8 66. E 39. 5 7 (75) E20 38} 64.5 14.1 78.6 21.4 s 0.68 D.M.F. (15)E20 (0.33) 115 62 3 2O 5 72 8 27 2 9 0.532 D.M.F. (15) H 0 (1.2) 28 213394 6&7 m7 10-.-" 0.532 D.M.F. (15) E 0 (1.2) 116 53.6 21.9 75.6 24.5

11-.- 0.532 D.M.F. (16) B20 (1.2) 63.7 17.8 71.6 28.5

0.56 12 0. 632 D.M.F. (16) E 0 (1.2) H((JO K) 27Y 100 32.0 37.6 69.628.0

0.566 1a.--- 0.532 13.11.12 (15) E20 (1.2) K011001116) f -g- 53.4 21. a14.9 25.1 14.. 60. 0 D.M.F. (850) H10 (35) KOAe (92.0) 4 69. 7 14. 7 74.4 28. 7 15..- 0. 532 D.M.F. (1 20 (1.2) KOAe (0.66) 3 115 69.3 10.3 69.627.6 0. 486 HCOzH (20) H 0 (2.5) KHOO; (0.2) 5% 100 44. 1 1.9 46.0 49. 6

The 21-acetoxylation was carried out as described in Example 18, onecrystallisation from acetone-petroleum (B.P. 40-60") afforded the2l-acetate, M.P. 170-173".

EXAMPLE 20 21-acetoxy-3a-hydroxy-5a-pregnane-11,20-dione via atrichloroethoxycarbonyl derivative 2,2,2-trichloroethylchloroformate(1.1 ml.) was added to a cooled, stirred, solution of3u-hydroxy-5a-pregnane- 11,20-dione in pyridine (0.74 ml.) and dioxan(5.6 ml.). After 10 minutes dilute hydrochloric acid (14.5 ml.) wasadded and the solution was heated at 100 for 30 minutes. The resultingoil crystallised on cooling to give 3oz- (2,2,2-trichloroethoxycarboyloxy) a pregnane 11,20-dione (1.45 g.), M.P.130-131, [M +56 (C. 1.0, CHCl (Found: C, 56.0%; H, 6.5%; Cl, 21.1%. C HCl O requires C, 55.6%; H, 6.6%; Cl, 20.7%.)

21-acetoxylation of this compound (0.5 g.,) using the proceduredescribed in Example 18 gave a syrupy residue that crystallised on theaddition of ether and petroleum. Recrystallisation from ether-petroleum(B.P. 4060) gave 21 acetoxy-3u-(2,2,2-trichloroethoxycarbonyloxy)-5a-pregnane-1l,20-dione (0.325 g.) M.P. 143-146 (decomp.), [a1 +75.2 (C.1.0, CI-ICl (Found: C, 55.1%; H, 6.0%; Cl, 18.6%. C H C1 O requires C,54.3%; H, 6.4%; Cl, 19.2%).

Removal of the 2,2,2 trichloroethoxycarbonyl group was effected bystirring a solution of the steroid (0.10 g.) in ethanol (2 ml.) andglacial acetic acid (2.5 ml.) for 5 hours with addition of zinc dust(0.3 g.) during this period. The solids were filtered off, washed withethanol and the combined filtrate was reduced in volume in vacuo.Addition of water to the residual solution gave 21-acetoxy- 3a hydroxy5m-pregnane-1L20-dione (0.036 g.), M.P. 168-172.".

EXAMPLE 21 21-acetoxy-5a-pregnan-3u-ol-11,20-dione Dried yeast(Saccharomyces cerevisiae 50 g.) was stirred at room temperature withtap water (2 1.) containing sucrose (200 g.) and di-ammonium hydrogenphosphate (4 g.). After two hours 2l-acetoxy-5u-pregnane-3,11,20- trione(1 g.), (Mancara et al., J. Amer. Chem. Soc., 1955, 77, 5669) in ethanol(100 ml.) was added. Th'e fermentation was stirred at room temperaturefor a further 24 hours, the yeast was removed by filtration, partiallydried at the pump and extracted with hot chloroform (4X 250 ml.). Theextracts were shaken with the filtrate, washed with water, dried (Na SOand evaporated to a brown gum (634 mg.). This was subjected topreparative thinlayer chromatography which yielded two pure substances.Of these the less polar was the starting material21-acetoxy-5a-pregnane-3,11,20-trione, (68 mg); which was recrystallisedfrom acetone/hexane as colourless needles, M.P. 169-172; [a] +127.5, (C.0.87, CHCIg). Gasliquid chromatography confirmed that this was identicalwith the starting material.

The more polar substance (70 mg.) was recrystallised from acetone/hexaneto afford 21-acetoxy-5a-pregnan-3aol-11,20-dione (57 mg.) as colourlessneedles, M.P. 179- 182; [:11 +107", (C. 1.09, CHCl Gas-liquidchromatography confirmed the identity of this material.

EXAMPLE 22 21-acetoxy-5a-pregnan-3a-ol-11,20-dione (a)21-bromo-5u-pregnan-3a-ol-11,20-dione: Soc-pregnan-3a-0l-l1,20-dione (1g., 3 mmoles) in stirred methanol (7 ml.) at 30 was treated with acetylchloride (1 drop). After two minutes bromine (0.19 ml., 3.52 mmoles) inmethanol (4.5 ml.) was added dropwise, the solution being allowed todecolourise between the addition of each drop. The resulting clearsolution was poured into chloroform (100 ml.), washed with water (3X 50ml.), dried. (Na 'SO and evaporated to a white froth (1.40 g.).Preparative thin-layer chromatography afforded 21-bromo- 145a-pregnan-3a-0l-11,20-dione (715 mg.) which crystallised fromchloroform/ether as clusters of colourless needles, M.P. 160-163"; [u]+109 (C. 0.82, CHCl (Found: C, 61.0%; H, 7.9%; Br, 19.7%. C H BrOrequires C, 61.3%; H, 7.6%; Br, 19.45%.)

A second, unstable substance (415 mg.) isolated from this reaction wasexamined spectroscopically and identified as17a-bromo-5a-pregnan-3a-ol11,20-dione.

(b) 21-acetoxy-5a-pregnan-3u-ol-11,20-dione: Sa-preg- EXAMPLE 2321-acetoxy-5a-pregnan-3a-ol-11,20-dione 5oz pregnan-3a-ol-11,20-dione (5g., 15.0 mmoles) in stirred methanol (35 ml.) at 0 was treated with 5drops of a 50% w./v. solution of hydrogen bromide in glacial aceticacid. After several minutes, bromine (0.95 ml., 2.815 g., 17.6 mmoles)in methanol (22.5 ml.) was added portionwise over ca. 10 minutes. Thesolution was left stirring until the colour disappeared and then pouredinto water. The product was isolated by filtration, washed with waterand dried in vacuo at 40 for five hours. Final drying was overphosphorus pentoxide in a desiccator (overnight). Yield: approximatelyquantitative.

The crude bromo-intermediate was dissolved in acetone ml., dried overpotassium carbonate) and refluxed in the presence of potassium acetate(10 g.) for four hours.

The reaction mixture was poured into water (1 l.) and extracted withether (300 ml. and 250 ml.). The ether was dried over anhydrousmagnesium sulphate, filtered and evaporated under reduced pressure.

The residual foam was recrystallised from acetone-petroleum ether togive 2l-acetoxy-5u-pregnan-3a-ol-11,20- dione as white needles. Yield,63%; M.P. 173-175 [ab +109 (c. 1.0, CHCI EXAMPLE 2421-propionyloxy-5a-pregnan-3a-ol-11,20-dione 5a-pregnan-3a-ol-11,20-dione (2 g., 6 mmoles) in methanol (14 ml.) at 30 was treated withacetyl chloride (2 drops). The solution was stirred for two minutes andwas treated dropwise with bromine (0.38 ml., 7 mmoles) in methanol (9ml.) in the manner described above. The reaction mixture was poured intostirred water (250 ml.). The product was isolated, washed and dried atthe pump and redried over phosphorus pentoxide in vacuo to afford awhite powder (2.49 g.). This was refluxed with propionic acid (11.1 ml.,0.15 mmole) and triethylamine (7.25 ml., 0.1 mole) in dry acetone (60ml.). After five hours the solution was poured into chloroform (300ml.), washed with aqueous potassium hydrogen carbonate (2X 200 ml.) andwith water (2X 200 ml.) dried (Na SO and evaporated to a white froth(2.59 g.). Preparative thin-layer chromatography afforded material whichon recrystallisation from chloroform/ether/hexane gave21-propionyloxy-5a-pregnan-3a-ol-11,20-dione 5 89 mg.) as colourlessirregular prisms, M.P. 159-170; [ab +99, (0. 0.92, CHCI (Found: C,70.5%; H 8.9%. C H O AH O requires C, 70.45%; H, 9.0%.)

EXAMPLE 25 21-isobutyryloxy-5a-pregnan-3a-ol- 1 1,20-dione 5o:pregnan-3u-ol-11,20-dione (2 g., 6 mmoles) in ml., 0.15 mole) andtriethylamine (7.25 ml., 0.10 mole) in dry acetone (60 ml.). After fourhours the solution was poured into chloroform (300 ml.), washed withaqueous potassium hydrogen carbonate (2X 200 ml.), with water (2X 200ml.), dried -(Na SO and evaporated to a white froth (2.54 g.).Preparative thin-layer chromatography afforded2l-isobutyryloxy-5a-pregnan-3a-ol-11, -dione (1.45 g.) as a white froth,[0:1 +93.5 (c. 0.66, CI-IC1 (Found: C, 70.4%; H, 8.8%. C H O /2H Orequires C, 70.25%; H, 9.2%.)

EXAMPLE 26 2 l-benzoyloxy-5a-pregnan-3 a-ol- 1 1,20-di0ne 50:.pregnan-3a-ol-1L20-dione (2 g., 6 mmoles) in methanol (14 ml.) wastreated with acetyl chloride (2 drops) and bromine (0.38 ml., 7 mmoles)as described 25 above. Isolation of the crude bromination product in theusual manner afforded a white powder (2.498 g.). This was refluxed wtihbenzoic acid (18.3 g., 0.15 mole) and triethylamine (7.25 ml., 0.1 mole)in-dry acetone (100 ml.). After five hours the solution was poured intochloroform (500 ml.), washed with aqueous sodium hydrogen carbonate (2x200 m1.) and with water (3X 200 ml.), dried (Na -S0 and evaporated to awhite froth. Preparative thin-layer chromatography afforded21-benzoyloxy 5a-pregnan-3a-ol-l1,20-dione (1.27 g.) as a white froth,[a] +104 (c. 0.65, CHCl (Found: C, 72.6%; H, 7.7%. C H 0 /2H O requiresC, 72.85%; H, 8.05%.)

EXAMPLE 27 2l-isobutyryloxy-5a-pregnan-3a-ol-l1,20-dione 3-nitrate (i)Fuming nitric acid (1.3 ml.) Was added to stirred acetic anhydride (5ml.). The solution was cooled to 5 and 21acetoxy-Sa-pregnan-3a-ol-11,20-dione (500 mg., 1.28 mmoles) inchloroform (2.5 ml.) was added. The resulting solution was stirred at-5" for an hour before being poured into dilute aqueous sodium hydroxide(100 ml.), extracted with chloroform (2X 75 ml.) and the extract washedwith aqueous sodium bicarbonate (50 ml.), with water (3X 50 ml.), dried(Na SO and evaporated to a gum (527 mg.). Crystallisation fromether/acetone afforded 21 acetoxy-5a-pregnan-3a-ol-l1,20-dione 3-nitrate (386 mg.) as colourless needles, M.P. 147-149"; [e1 +103 (c. 1.06,C'HClg). (Found: C, 63.6 H, 7.5%; N, 3.1%. C H NO requires C, 63.45%; H,7.65%; N, 3.2%.)

(ii) 5a-pregna-3u,21-diol-11,20-dione 3-nitrate: (a) 21-aeetoxy-5a-pregnan-3u-ol-l1,20-dione S-nitrate (837 mg., 2 mmoles) inethanol (42 mg.) and tetrahydrofuran (42 ml.) was stirred with 10%aqueous potassium hydrogen carbonate (4 ml.) and 2 N aqueous sodiumhydroxide (2 ml.). After three hours glacial acetic acid (1 ml.) wasadded, the solution was poured into water (400 ml.) and extracted withchloroform (3X 120 ml.). The extracts were washed with water (2X 50ml.), dried (MgSO and evaporated to a froth. Preparative thinlayerchromatography afforded pure material which on recrystallisation fromether/acetone gave Sat-pregna- 3a,2ldiolll,20-dione 3-nitrate (219 mg.)as colourless irregular prisms, M.P. 172-176; [ed -l-9l (C. 0.97, CHCI(Found: C, 63.9%; H, 7.8%; N, 3.5%. C l-1 N13 requires C, 64.1%; H,7.95%; N, 3.55%.)

(b) 2l-acetoxy-5a-pregnanitx-ol-ll,20-dione (5 g., 13.3 moles) inchloroform (25 ml.) was added to a stirred solution of fuming nitricacid (13 ml.) in acetic anhydride (50 ml.) at 5. The reaction mixturewas stirred at 5 for an hour, poured into stirred aqueous sodiumhydroxide (1 l.) and extracted with chloroform (2X 200 ml.). The extractwas washed with aqueous sodium hydrogen carbonate (100 ml.) and withwater (2X 100 ml.), dried (Na S0 and evaporated to a white froth. Thiswas dissolved in methanol (500 ml.), the solution flushed with nitrogenand stirred with 10% aqueous potassium hydrogen carbonate (17.5 ml.) forfour hours. Glacial acetic acid (3 ml.) was added, the solutionevaporated to small bulk, poured into water (1 l.) and extracted withchloroform (2X 200 ml.). The extract was washed with water (2x 100 ml.),dried (Na SO and evaporated to a white froth. crystallisation fromacetone/ ether gave 5a-pregna-3a,21-diol- 11,20- dione 3-nitrate (4.31g.) as colourless irregular prisms, M.P. 174-181".

(iii) 2l-isobutyryloxy-5a-pregnan-3ot-ol-11,20-dione 3- nitrate:5ot-pregna-3a,21-diol 11,20-dione 3-nitrate (2.0

0 g., 5.08 mmoles) in dry pyridine (20 ml.) was treated 5 in Example 31.

with isobutyryl chloride (2 ml.). The pink solution was allowed to standat room temperature for 20 hours before being poured into stirred waterand acidified with dilute hydrochloric acid. The product was isolated,washed thoroughly with water and dried at the pump. Recrystallisationfrom acetone/hexane afforded21-isobutyryloxy-5a-pregnan-3u-ol-l1,20-dione 3-nitrate (1.01 g.) ascolourless needles, M.P. 1 67- 169"; [otJ +9=7.5 (0. 1.48, CHCl (Found:C, 64.5%; H, 7.8%; N,

3.2%. C25H37NO7 requireS C, H, N,

(iv) 21-isobutyryloxy-5u-pregnan-3a-ol 11,20 dione: 21isobutyryloxy-Sa-pregnan-3a-ol-l1,20-dione 3-nitrate (1.35 g., 2.91mmoles) in glacial acetic acid ml.) was 35 stirred for an hour at roomtemperature with zinc powder (4 g.). The zinc was removed, washed withhot chloroform (200 ml.) and the combined washings and filtrates werewashed with water (4X 100 ml.) dried (Na SO and evaporated to a whitefroth. Preparative thin-layer chromatography alforded 21-isobutyryloxy cpregnan- EXAMPLE 28 3ct-hydroxy-5a-pregn-16-ene-1 1,20-dione and 5tit-pregna- 2, 1*6-die11e 1 l ,20-dione A stirred mixture of Zip-toluenep sulphonyloxy5a- 50 pregn-16-ene- 11,20-dione (627 g.), potassiumacetate (918 g.), dimethylformamide (4.25 l.) and water (425 ml.) washeated on the steam bath for 4 hrs. Most of the dimethylformamide wasremoved under reduced pressure and water was added to the residue withstirring. The solid (420 g.) was collected, washed and dried at 40 invacuo. This material in peroxide free dioxan (7 1.) was flushed withnitrogen and a solution of potassium hydroxide (200 g.) in water (2 l.)was added. The mixture was stirred and heated at 50-60 for 7 hrs. and

then left at room temperature overnight. Acetic acid (50 ml.) was addedand the precipitated solid filtered 01f, washed with water and dried.The dry solid was heated under reflux with benzene (2 l.) for 2 hrs. themixture cooled and filtered to give 3a-hydroxy-5a-pregn-l6-ene-11,20-dione (215 g.).

Benzene extracts from several similar experiments were combined andevaporated. The crude solid was redissolved in hot benzene and petroleum(B.P. 60-80") was added until the solution was just clear at ambienttemperature (an insoluble residue was removed by filtration diene.Elution was terminated when thin layer chromatography indicated thepresence of slower running components in the eluate. The combinedfractions were evaporated and twice crystallised from benzene-petroleum(B.P. 60-80) to give 5a-pregna-2,l-6-diene-11,20-dione as colourlesscrystals, M.P. 176177, [:1 +159 (C. 1.0 in CHCl a (EtOH) 233.5 nm. (e9150') (Found: C, 80.5%; H, 8.9%. C H O requires C, 80.8%; H, 9.0%.)

EXAMPLE 29 a-pregna-3 a,21diOl11,20-di0n 2 l -hemisuccinate5u-pregna-3a,21-diol-11,20-dione 3-nitrate 2l-hemisuccinate (1.03 g.,2.09 mmoles) and zinc powder (3 g.) Were stirred with acetic acid (25ml.) for 90 minutes. The zinc was removed, washed with chloroform (100ml.), 2 N aqueous hydrochloric acid (200 ml.) and chloroform (100 ml.).The combined filtrates were equilibrated and the organic phase waswashed with water (3X 100 =ml.), dried (Na 'SO and evaporated to a Whitefroth. Crystallisation from benzene/hexane/chloroform gave5a-pregna-3a,21-diol-11,20-dione 21-hemisuccinate (800 mg.) ascolourless needles, M.P. 166-168"; [@1 +90.5 (C. 1.32 in CHCl (Found: C,66.9%; H, 8.0%. C25H360'1 requires C, 66.95%; H, 8.1%.)

The starting material for this preparation was obtained from5a-pregna-3a,21-diol-1'1,20-dione 3-nitrate (see Example 33ii) asdescribed below:

5a-pregna-3a,2l-diol-l1,20-dione 3-nitrate (2 g., 5.08 mmoles) andsuccinic anhydride (2 g., 20 mmoles) in dry pyridine (20 ml.) wereallowed to stand at room temperature for 18 hours. The solution waspoured into stirred water (300 ml.) which was then acidified. After twohours, the precipitate was collected, washed well with water and dried.Recrystallisation from benzene/hexane gave5tz-pregna-3a,21-diol-11,20-dione 3-nitrate 21-hemisuccinate (1.51 g.)as colourless micro-needles; M.P. l60-163; [111 +89.5 (C. 1.14, CHCl(Found: C, 60.8%; H, 7.3%; N, 2.6%. C H NO requires C, 60.8%;H,7.15%;N,2.85%.)

EXAMPLE 30 0.03 g. of steroid I, finely divided in an air-attrition milland having an approximate mean particle diameter of 5 was mixed with 2g. of Cremophor EL by mechanical agitation and heated to 70 in anatmosphere of nitrogen. Heating and agitation was continued until thesteroid had dissolved. The solution was diluted with sterile distilledwater containing 0.025 g. of sodium chloride to gain a final volume ofmL, and stirring continued until the solution was homogeneous.

EXAMPLE 31 0.035 g. of steroid I reduced in size as in Example 30 mixedwith 0.035 g. of steroid II (R=CH CO) reduced in size as for steroid I.The steroids are added to 10 ml. of a 20% w./v. solution of Cremophor ELcontaining 0.025 g. of sodium chloride and the mixture mechanicallystirred for at least 24 hours. Any traces of insoluble residue arefiltered 011? using a sintered glass filter.

EXAMPLE 32 13.5 g. of ground steroid I and 4.5 g. of steroid II (R=CHCO) are mixed by mechanical agitation with 300.0 g. of Cremophor EL at70 C. in an atmosphere of nitrogen. Heating and agitation are continueduntil the steroids have completely dissolved. The mixture is dilutedWith sterile distilled water containing 3.75 g. of sodium chloride togive a final volume of 1500 ml. Stirring is continued until the solutionis homogeneous.

EXAMPLE 33 0.045 g. of steroid I and 0.015 g. of steroid II (R=CH CO-)are dissolved in 2 ml. of acetone at 20 C. The resultant solution isadded to 1 g. of Cremophor EL at 20 C. and stirred until homogeneous.The acetone is removed by a 18 vigorous stream of nitrogen. The solutionis diluted with sterile distilled water containing 0.0125 g. of sodiumchloride to give a final volume of 5 ml. Similar solutions were preparedusing chloroform or methylene chloride in place of acetone.

EXAMPLE 34 0.09 g. of ground steroid I are mixed with 0.03 g. of groundsteroid II (R=CH CO) and this added to 2.0 g. of Tween 80. As in Example33, the mixture is mechanically agitated at 70 C. in a stream ofnitrogen until the steroids have dissolved. The mixture is diluted withsterile distilled water containing 0.025 g. of sodium chloride to give afinal volume of 10 ml.

EXAMPLE 35 0.045 g. of steroid I and 0.015 g. of steroid II (R: (CHCI-ICO) are formulated as in Example 33. Similar solutions are obtainedusing steroid II wherein R=C H CO,

HO CCH CH CO- or C H CO-.

EXAMPLE 36 0.045 g. of steroid I and 0.015 g. of steroid 11 (R=CH CO)are dissolved in 2 ml. of acetone at 20 C. The resulting solution isadded to 1 g. of Tween 40 at 20 C. and stirred until homogeneous. Theacetone is removed by a vigorous stream of nitrogen. The solution isdiluted with sterile distilled water containing 0.025 g. of sodiumchloride to give a final volume of 10 ml.

EXAMPLE 37 0.036 g. of ground steroid I are mixed with 0.012 g. ofground steroid II (R=CH CO). This is added to 0.8 g. of Tween 60. Themixture is mechanically agitated at 70 C. in a stream of nitrogen untilthe steroids are dissolved. The mixture is diluted with steriledistilled water containing 0.025 g. of sodium chloride to give a finalvolume of 10 ml.

EXAMPLE 38 16 mg. of steroid I and 4 mg. of steroid II (R=CH CO) weredissolved in 0.2 ml. of acetone, and 0.2 ml. of Cremophor EL was mixedwith this solution. The acetone Was removed by passing a stream ofnitrogen through the mixture. The resulting solution was mixed with 0.8ml. of sterile water.

EXAMPLE 39 0.135 gram steroid I and 0.045 gram of steroid II, (R=CH CO),are dissolved in 2 mls. of acetone at 20 C. The resulting solution isadded to 3 grams of Cremophor EL at 20 C. and stirred until homogeneous.The acetone is removed by a vigorous stream of nitrogen. The solution isdiluted with sterile distilled water containing 0.025 gram of sodiumchloride to give a final volume of 10 mls.

EXAMPLE 40 0.045 gram of ground steroid I are mixed with 0.012 gram ofground steroid II (R=CH CO), and the mixture added to 1 gram ofCremophor EL. The mixture is mechanically agitated at 70 C. in a streamof nitrogen until the steroids have dissolved. The mixture is dilutedwith sterile distilled water containing 0.025 gram of so dium chlorideto give a final volume of 10 mls.

We claim:

1. A method of inducing anaesthesia in an individual, man or animal, tobe anaesthetised, comprising parenterally administering to theindividual an aqueous solution containing at least 1 mg./ml. of3a-hydroxy-5ot-pregnane-11, 20-dione and an amount of a parenterallyacceptable nonionic surface active agent having the effect ofsolubilizing said 3a-hydroxy-5a-pregnane-11,20-dione.

2. A method as claimed in claim 1 wherein the surface active agent hasan HLB value of at least 9.

3. A method as claimed in claim 2 wherein the surface active agent hasan HLB value of from 9-18.

4. A method as claimed in claim 1 wherein the surface active agent isselected from the group consisting of a polyoxyethylated castor oilcontaining from 35-45 oxyethylene groups and a polyoxyethylated fattyacid ester containing from 12 to 18 carbon atoms of sorbitan ormannitan.

5. A method as claimed in claim 1 wherein the surface active agent isselected from the group consisting of a polyoxyethylated castor oilcontaining about 40 ethylene oxide units per triglyceride unit, andpolyoxyethylene sorbitan monooleate containing about 20 ethylene oxideunits.

6. A method as claimed in claim 1 wherein the surface active agentcomprises polyoxyethylene sorbitan monostearate containing about 20ethylene oxide units or polyoxyethylene sorbitan monopalmitatecontaining about 20 ethylene oxide units.

7. A method as claimed in claim 1 wherein said solution contains above5% by weight of surface active agent based on the total volume of thesolution in metric units.

8. A method as claimed in claim 7 wherein said solution contains above10% by weight of surface active agent.

9. A method as claimed in claim 7 wherein said solution contains notmore than 50% by weight of surface active agent.

10. A method as claimed in claim 9 wherein said solution contains notmore than 30% by weight of surface active agent.

11. A method as claimed in claim 7 wherein said solution contains aboutby Weight of surface active agent.

12. A method as claimed in claim 1 wherein said solution contains atleast 2 mg./ml. of 3u-hydroxy-5u-pregnane- 1 1,20-dione.

13. A method as claimed in claim 12 wherein said solution contains atleast 4 mgJml. of 3a-hydroxy-5apregnane-l 1,20-dione.

14. A method as claimed in claim 1 wherein said solu- 20 tion containsabout 20% by weight of a polyoxyethylated castor oil containing about 40ethylene oxide units per triglyceride unit based on the total volume ofthe solution in metric units.

15. A method as claimed in claim 1 wherein said solution contains about20% by weight of polyoxyethylene sorbitan monooleate containing about 20ethylene oxide units per triglyceride unit based on the total volume ofthe solution in metric units.

References Cited UNITED STATES PATENTS 2,880,138 2/1959 Johnson 424-240X 3,180,797 4/ 1965 Cachillo et al. 42424O X 3,337,400 8/1967 Smith424-240 FOREIGN PATENTS 6,555 2/ 1969 France. 834,913 5/1960 GreatBritain. 941,694 12/ 1963 Great Britain.

OTHER REFERENCES Kappas et al.: A.M.A. Arch. Intern. Med. :701-708 (May1960) Fever Producing Steroids of Endogenous Origin in Man.

Campbell et al.: Brit. J. Anaesth. 43:14, 24 (1971) A PreliminaryClinical Study of CT 134l-A steroid Anaesthetic Agent.

Child et al.: Brit. J. Anaesth. 43:2-13 (1971) The PharmacologicalProperties in Animals of CT 1341, A New Steroid Anaesthetic Agent.

Clarke et al.: Brit. J. Anaesth. 43:947-952 (1971) Clinical Studies ofInduction Agents-XXXIX: CT 1341, A New Steroid Anaesthetic.

Atkinson et al.: J. Med. Chem. 8:426-432 (1965) Action of Some Steroidson the Central Nervous System of the Mouse II. Pharmacology.

SHEP K. ROSE. Primary Examiner US. Cl. X.R.

